builtin walkSync for this.output, this.input or `fake fs`

[lifeart]

Reading API updates regarding this.input, this.output. I'was checked original broccoli plugin documentation on website and seen such example:

https://github.com/broccolijs/broccolijs.github.io/edit/code/src/content/plugins.md

build() {
        const walkOptions = {
            includeBasePath: true,
            directories: false,
            globs: this.fileMatchers,
        };

        const content = this.inputPaths
            .reduce((output, inputPath) => output + this.joinSeparator +
                walkSync(inputPath, walkOptions)
                    .map(file => fs.readFileSync(file, { encoding: 'UTF-8' }))
                    .join(this.joinSeparator),
            '');

        fs.writeFileSync(`${this.outputPath}/${this.outputFile}`, content);
    }

How we will convert it into new api? without fs usage inside walkSync?

// @SparshithNR @stefanpenner

[SparshithNR]

@lifeart As of now, we do not have walksync as you mentioned. But we do have entries in this.input. So we can change the build code slightly to achieve the same goal as before.

 build() {
        const walkOptions = {
            includeBasePath: true,
            directories: false,
            globs: this.fileMatchers,
        };

        const content = this.input.entries('./', walkOptions)
                    .map(file => this.input.readFileSync(file.relativePath, { encoding: 'UTF-8' }))
                    .join(this.joinSeparator);

        fs.writeFileSync(`${this.outputPath}/${this.outputFile}`, content);
    }